A186782 Primes of the form k*6^m-1 with k prime and m an integer.

2, 11, 17, 29, 41, 71, 101, 107, 113, 137, 173, 179, 251, 257, 281, 317, 353, 401, 431, 467, 617, 641, 647, 653, 677, 683, 761, 821, 827, 941, 977, 1181, 1193, 1361, 1373, 1433, 1511, 1613, 1697, 1877, 1901, 1907, 2081, 2153, 2237, 2273, 2297, 2333, 2381, 2411, 2591

Offset

1,1

Comments

Companion sequence to A185069.

Links

Table of n, a(n) for n=1..51.

Example

5*6^1-1 = 29 is prime and therefore a term.
7*6^2-1 = 251 is prime and therefore a term.
17*6^13-1 = 222031798271 is prime and therefore a term (see also its companion in A185069).

Mathematica

maxM = 4; p = Prime[Range[PrimePi[2*6^maxM]]]; Sort[Flatten[Table[Select[p + 1, PrimeQ[#/6^k] &], {k, 0, maxM}] - 1]] (* T. D. Noe, Feb 28 2011 *)

Prog

(Magma) IsA186782:=function(n); k:=n+1; while k mod 6 eq 0 do k:=(k div 6); end while; return IsPrime(k); end function; [ n: n in PrimesUpTo(3000) | IsA186782(n) ]; // Klaus Brockhaus, Mar 01 2011

Crossrefs

Cf. A185069.

Sequence in context: A214934 A233866 A117155 * A141176 A118839 A091735

Adjacent sequences: A186779 A186780 A186781 * A186783 A186784 A186785

Keyword

nonn

Author

Gilbert Mozzo, Feb 26 2011

Status

approved